Process for Reducing Oxygenate Content of Hydrocarbon Feed

ABSTRACT

The present disclosure provides a process for reducing oxygenate content of hydrocarbon feed. The process comprises passing and heating the hydrocarbon feed over ion exchange resin resident in a reactor, maintained at a temperature in the range of 90 to 140° C. and a predetermined pressure, at a predetermined liquid hourly space velocity to obtain a heated intermediate fluid. The heated intermediate fluid is cooled to obtain a cooled intermediate fluid. The cooled intermediate fluid is mixed with water to obtain a mixture. The mixture is allowed to settle to obtain an aqueous phase and an organic phase. The aqueous phase is separated from the organic phase to obtain hydrocarbon feed with reduced oxygenate content. The process is simple and environment friendly, enabling removal of 70-90% of the oxygenate content from the hydrocarbon feed.

FIELD

The present disclosure relates to hydrocarbons and petrochemicals.

DEFINITIONS

The unit “ppmw” represents parts per million weight, which is a subunitof ppm used to express part of weights like milligrams per kilogram(mg/kg).

Oxygenates refer to oxygen containing compounds like ethers, alcohols,acids present in hydrocarbon feed.

The unit “barg”, a unit of gauge pressure, is used for expressingpressure in bars above ambient or atmospheric pressure.

BACKGROUND

Olefins are major building blocks for various petrochemicals. Owing torelatively high reactivity of olefins, their demand is alwaysincreasing. Different olefin products such as ethylene, propylene,butadiene, butane, butene, isoprene, pyrolysis gasoline, and the likeare produced using steam cracker.

Olefins are produced in the stream cracker using naphtha as a feedstock.Naphtha is an intermediate hydrocarbon liquid stream obtained duringdistillation of crude oil or thermal and/or catalytic cracking ofhydrocarbon streams. Naphtha contain large amount of oxygen compounds,commonly called as oxygenates. These oxygenates are undesiredcontaminants for naphtha cracker units, and its downstream equipment.Naphtha fraction with relatively high concentration of oxygenates, asimpurities, is of particular concern to naphtha crackers, and variousother catalytic conversion processes, as the oxygen containing compoundsincrease corrosion, and fouling rates in the downstream equipment. Theoxygen containing compounds are also responsible for poisoning thecatalyst. The acceptable level of oxygenates in the hydrocarbon feed is50 ppmw.

Hence, there is a need to provide a process for reducing the oxygenatecontent of the hydrocarbon feed.

Objects

Some of the objects of the present disclosure, which at least oneembodiment herein satisfies, are as follows:

An object of the present disclosure is to provide a process for reducingthe oxygenate content of hydrocarbon feed.

Another object of the present disclosure is to provide a process that issimple and environment friendly for reducing the oxygenate content ofhydrocarbon feed.

Other objects and advantages of the present disclosure will be moreapparent from the following description, which is not intended to limitthe scope of the present disclosure.

SUMMARY

The present disclosure provides a process for reducing oxygenate contentof hydrocarbon feed. The process comprises the following steps:

-   -   (i) passing and heating the hydrocarbon feed over ion exchange        resin resident in a reactor, maintained at a temperature in the        range of 90 to 140° C. and at a pre-determined pressure, at a        predetermined liquid hourly space velocity to obtain a heated        intermediate fluid;    -   (ii) cooling the heated intermediate fluid to obtain a cooled        intermediate fluid;    -   (iii) mixing the cooled intermediate fluid with water to obtain        a mixture;    -   (iv) allowing the mixture to settle to obtain an aqueous phase        and an organic phase; and    -   (iv) separating the aqueous phase from the organic phase to        obtain hydrocarbon feed with reduced oxygenate content.

In accordance with the present disclosure, the oxygenate in thehydrocarbon feed comprises at least one of methyl tertiary butyl ether(MTBE) and tertiary amyl methyl ether (TAME).

Typically, in accordance with the present disclosure, the oxygenate inthe hydrocarbon feed comprises at least one of methanol, ethanol,1-propanol, 2-butanol, 1-butanol and tertiary amyl alcohol.

Typically, in accordance with the present disclosure, the amount of theoxygenate content in the hydrocarbon feed is in the range of 51 to 350ppmw.

Typically, in accordance with the present disclosure, the amount of theoxygenate content in the hydrocarbon feed with reduced oxygenate contentis in the range of 4 to 50 ppmw.

Typically, in accordance with the present disclosure, the ion exchangeresin is a cation exchange resin.

Typically, in accordance with the present disclosure, the ion exchangeresin is a macroporous polymeric exchange resin.

Typically, in accordance with the present disclosure, the ion exchangeresin is a macroporous polymeric sulphonic acid exchange resin.

Typically, in accordance with the present disclosure, the processcomprises a pre-step of drying the ion exchange resin before using it instep (i).

Typically, in accordance with the present disclosure, the predeterminedpressure is in the range of 4 to 10 barg.

Typically, in accordance with the present disclosure, the predeterminedliquid hourly space velocity is in the range of 0.5 to 15 per hour.

Typically, in accordance with the present disclosure, the hydrocarbonfeed is petrochemical naphtha comprising C5 to C8 hydrocarbons.

Typically, in accordance with the present disclosure, the reactor is afixed bed reactor.

Typically, in accordance with the present disclosure, wherein quantityof the water used in step (iii) is in the range of 2.5 to 10 vol % ofthe hydrocarbon feed, wherein the water used in step (iii) isdemineralized water.

DETAILED DESCRIPTION

Petrochemical naphtha contain large numbers of oxygen containingcompounds or oxygenates, which are of particular concern to naphthacrackers, which makes the feedstock unsuitable for processing.Oxygenates tend to increase corrosion and fouling rates in downstreamequipment, while also reacting with the catalyst present in the naphthacracker and reducing its activity.

Oxygenates in hydrocarbon feed mainly include alcohols and ethers.Alcohols being water-soluble can be easily removed from the hydrocarbonfeed by washing, however ethers being essentially non-polar moleculesare sparingly soluble in water. As a result, the total oxygenates cannotbe removed from petrochemical naphtha stream by simply washing withwater.

Ethers can be removed from hydrocarbon feed easily if they are convertedto alcohols. Ethers can be converted to olefins and alcohols in thepresence of an acid. The alcohol molecules thus formed can be easilyremoved on washing the hydrocarbon feed with water.

The present disclosure envisages a process for reducing oxygenatecontent of hydrocarbon feed. The process is carried out by convertingethers in the hydrocarbon feed into alcohols using an ion exchange resinand then removing the alcohols in the hydrocarbon feed by washing withwater.

The process of the present disclosure comprises the following steps.Initially, the hydrocarbon feed is passed and heated over an ionexchange resin resident in a reactor maintained at a temperature in therange of 90 to 140° C. and a pre-determined pressure at a predeterminedliquid hourly space velocity to obtain a heated intermediate fluid.Preferably, the reactor is maintained at a temperature in the range of100 to 120° C., more preferably at 110° C. Typically, the reactor is afixed bed reactor. In an embodiment, the temperature of the reactor bedis measured by use of an axial thermocouple.

The heated intermediate fluid is collected after passing over the ionexchange resin. This heated intermediate fluid is cooled to obtain acooled intermediate fluid. Typically, the heated intermediate fluid iscooled to a temperature in the range of 30 to 40° C.

Further, the cooled intermediate fluid is mixed with water to obtain amixture, wherein the quantity of water is in the range of 2.5 to 10 vol% of the hydrocarbon feed. Typically, the mixing is carried out byshaking, stirring or by any other means. Typically, the water used isdemineralized water.

Furthermore, the mixture is allowed to settle to obtain an aqueous phaseand an organic phase. Thereafter the aqueous phase is separated from theorganic phase to obtain hydrocarbon feed with reduced oxygenate content.

As per an embodiment of the present disclosure, the amount of oxygenatecontent in the hydrocarbon feed is in the range of 51 ppmw to 350 ppmw.The oxygenate in the hydrocarbon feed comprises alcohols, ethers, acids,and the like. The oxygenate in the hydrocarbon feed comprise at leastone of methyl tertiary butyl ether (MTBE) and tertiary amyl methyl ether(TAME). The oxygenate in the hydrocarbon feed comprises at least one ofmethanol, ethanol, 1-propanol, 2-butanol, 1-butanol and tertiary amylalcohol.

Typically, the pre-determined pressure is in the range of 4 to 10 barg,preferably from 5 to 7 barg and more preferably 6 barg. Typically, thepredetermined liquid hourly space velocity is in the range of 0.5 to 15per hour. Preferably, the predetermined liquid hourly space velocity isin the range of 0.5 to 10 per hour.

Typically, the ion exchange resin is a cation exchange resin. Typically,the ion exchange resin is a macroporous polymeric resin. In anembodiment, the ion exchange resin used is macroporous polymericsulphonic acid exchange resin such as Amberlyst. The surface area of ionexchange resin is 50 m²/g, average pore diameter is 300 A°, total porevolume is 0.35 cc/g, the particle size is in the range of 0.3 to 1.20mm, and bulk density is 560 kg/m³.

In an embodiment of the present disclosure, moisture in the ion exchangeresin is at least below 3%. Preferably, the ion exchange resin is driedbefore use, so as to expel residual moisture, wherein the dried ionexchange resin is stored in a desiccator.

The present disclosure offers an integrated process for reducing theoxygenate content of the hydrocarbon feed. As per an embodiment of thepresent disclosure, the amount of oxygenate content in the hydrocarbonfeed with reduced oxygenate content is in the range of 4 to 50 ppmw. Theprocess of the present disclosure enables reduction of oxygenate contentof the hydrocarbon feed by an amount in the range of 70-90 wt %.

The process of the present disclosure can help to achieve desired degreeof oxygenate removal, thereby effectively improving the acceptability ofnaphtha stream as a feedstock. For most of naphtha conversion processes,the desired specification of oxygenate is less than 50 ppmw.

Typically, the hydrocarbon feed is comprised of straight run saturatedlight naphtha stream having boiling point in the range of 32 to 120° C.In one embodiment, the hydrocarbon feed is petrochemical naphthacomprising C5 to C8 hydrocarbon which further comprises C5-C8 normalparaffins, iso-paraffins, napthenes and C6-C7 aromatics. Typically, thehydrocarbon feed contains moisture at least below 160 ppmw and metalimpurity at least below 100 ppb. The metal impurity in the hydrocarbonfeed may be at least one of sodium, potassium, calcium and iron.

The present disclosure is further described in light of the followingexperiments which are set forth for illustration purpose only and not tobe construed for limiting the scope of the disclosure. The followingexperiments can be scaled up to industrial/commercial scale and theresults obtained can be extrapolated to industrial scale.

EXAMPLE 1

Hydrocarbon feed having an oxygenate content of 150 ppmw, moisturecontent of 160 ppmw and metal content of less than 100 ppb, was passedand heated over an Amberlyst resin present in a fixed bed reactor. Thereactor was maintained at 110° C. and 6 barg. The hydrocarbon feed waspassed at a liquid hourly space velocity (LHSV) of 7 per hour. The feedfrom the reactor was cooled to 30° C. and then mixed with 5 vol % ofwater. The resulting mixture was allowed to settle to obtain an aqueousphase and an organic phase. The organic phase was separated from theaqueous phase to obtain hydrocarbon feed with reduced oxygenate contenthaving 20 ppmw of oxygenate content.

EXAMPLE 2

Hydrocarbon feed having an oxygenate content of 150 ppmw, moisturecontent of 160 ppmw and metal content of less than 100 ppb, was passedand heated over an Amberlyst resin present in a fixed bed reactor. Thereactor is maintained at 110° C. and 6 barg. The effluent from reactorwas passed at a liquid hourly space velocity (LHSV) of 7 per hour. Thehydrocarbon stream from the reactor was cooled to 30° C. and then mixedwith 10 vol % of water. The resulting mixture was allowed to settle toobtain an aqueous phase and an organic phase. The organic phase wasseparated from the aqueous phase to obtain hydrocarbon feed with reducedoxygenate content having less than 20 ppmw of oxygenate content.

Technical Advances and Economical Significance

The present disclosure described herein above has several technicaladvantages including, but not limited to, the realization of a processfor reducing the oxygenate content of hydrocarbon feed, wherein theprocess:

-   -   enables removal of 70-90% of oxygenate content from the        hydrocarbon feed; and    -   is simple and environment friendly.

Throughout this specification the word “comprise”, or variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated element, integer or step, or group of elements, integers orsteps, but not the exclusion of any other element, integer or step, orgroup of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the useof one or more elements or ingredients or quantities, as the use may bein the embodiment of the invention to achieve one or more of the desiredobjects or results. While certain embodiments of the inventions havebeen described, these embodiments have been presented by way of exampleonly, and are not intended to limit the scope of the inventions.Variations or modifications to the formulation of this invention, withinthe scope of the invention, may occur to those skilled in the art uponreviewing the disclosure herein. Such variations or modifications arewell within the spirit of this invention.

The numerical values given for various physical parameters, dimensionsand quantities are only approximate values and it is envisaged that thevalues higher than the numerical value assigned to the physicalparameters, dimensions and quantities fall within the scope of theinvention unless there is a statement in the specification to thecontrary.

While considerable emphasis has been placed herein on the specificfeatures of the preferred embodiment, it will be appreciated that manyadditional features can be added and that many changes can be made inthe preferred embodiment without departing from the principles of thedisclosure. These and other changes in the preferred embodiment of thedisclosure will be apparent to those skilled in the art from thedisclosure herein, whereby it is to be distinctly understood that theforegoing descriptive matter is to be interpreted merely as illustrativeof the disclosure and not as a limitation.

1. A process for reducing oxygenate content of hydrocarbon feed, saidprocess comprising the following steps: (i) passing and heating saidhydrocarbon feed over ion exchange resin resident in a reactor,maintained at a temperature in the range of 90 to 140° C. and at apre-determined pressure, at a predetermined liquid hourly space velocityto obtain a heated intermediate fluid; (ii) cooling said heatedintermediate fluid to obtain a cooled intermediate fluid; (iii) mixingsaid cooled intermediate fluid with water to obtain a mixture; (iv)allowing said mixture to settle to obtain an aqueous phase and anorganic phase; and (iv) separating said aqueous phase from said organicphase to obtain hydrocarbon feed with reduced oxygenate content.
 2. Theprocess as claimed in claim 1, wherein said oxygenate in saidhydrocarbon feed comprises at least one of methyl tertiary butyl ether(MTBE) and tertiary amyl methyl ether (TAME).
 3. The process as claimedin claim 1, wherein said oxygenate in said hydrocarbon feed comprises atleast one of methanol, ethanol, 1-propanol, 2-butanol, 1-butanol andtertiary amyl alcohol.
 4. The process as claimed in claim 1, wherein theamount of said oxygenate content in said hydrocarbon feed is in therange of 51 to 350 ppmw.
 5. The process as claimed in claim 1, whereinthe amount of the oxygenate content in said hydrocarbon feed withreduced oxygenate content is in the range of 4 to 50 ppmw.
 6. Theprocess as claimed in claim 1, wherein said ion exchange resin is acation exchange resin.
 7. The process as claimed in claim 1, whereinsaid ion exchange resin is a macroporous polymeric exchange resin. 8.The process as claimed in claim 1, wherein said ion exchange resin is amacroporous polymeric sulphonic acid exchange resin.
 9. The process asclaimed in claim 1, wherein said process comprises a pre-step of dryingsaid ion exchange resin before using it in step (i).
 10. The process asclaimed in claim 1, wherein said predetermined pressure is in the rangeof 4 to 10 barg.
 11. The process as claimed in claim 1, wherein saidpredetermined liquid hourly space velocity is in the range of 0.5 to 15per hour.
 12. The process as claimed in claim 1, wherein saidhydrocarbon feed is petrochemical naphtha comprising C5 to C8hydrocarbons.
 13. The process as claimed in claim 1, wherein saidreactor is a fixed bed reactor.
 14. The process as claimed in claim 1,wherein quantity of the water used in step (iii) is in the range of 2.5to 10 vol % of the hydrocarbon feed, wherein the water used in step(iii) is demineralized water.